package com.xzhang.util;

import java.util.Random;

import org.apache.commons.lang.StringUtils;

/**
 * @author huangj 2009-12-16
 */
public class RandomUtils {

	public static final String allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

	public static final String letterChar = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

	public static final String numberChar = "0123456789";

	/**
	 * 生成一个10位数的随机数
	 * 
	 * @return
	 */
	public static String generateTmpEntityId() {

		return generateString(10);
	}

	/**
	 * 返回一个定长的随机字符串(只包含大小写字母、数字)
	 * 
	 * @param length
	 *            随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateString(int length) {

		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for ( int i = 0; i < length; i++ ) {
			sb.append(allChar.charAt(random.nextInt(allChar.length())));
		}
		return sb.toString();
	}

	public static String generateNumString(int length) {

		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for ( int i = 0; i < length; i++ ) {
			sb.append(numberChar.charAt(random.nextInt(numberChar.length())));
		}
		return sb.toString();
	}

	/**
	 * 返回一个定长的随机纯字母字符串(只包含大小写字母)
	 * 
	 * @param length
	 *            随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateMixString(int length) {

		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for ( int i = 0; i < length; i++ ) {
			sb.append(allChar.charAt(random.nextInt(letterChar.length())));
		}
		return sb.toString();
	}

	/**
	 * 返回一个定长的随机纯小写字母字符串
	 * 
	 * @param length
	 *            随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateLowerString(int length) {

		return generateMixString(length).toLowerCase();
	}

	/**
	 * 返回一个定长的随机纯大写字母字符串
	 * 
	 * @param length
	 *            随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateUpperString(int length) {

		return generateMixString(length).toUpperCase();
	}

	/**
	 * 生成一个定长的纯0字符串
	 * 
	 * @param length
	 *            字符串长度
	 * @return 纯0字符串
	 */
	public static String generateZeroString(int length) {

		StringBuffer sb = new StringBuffer();
		for ( int i = 0; i < length; i++ ) {
			sb.append('0');
		}
		return sb.toString();
	}

	/**
	 * 根据数字生成一个定长的字符串，长度不够前面补0
	 * 
	 * @param num
	 *            数字
	 * @param fixdlenth
	 *            字符串长度
	 * @return 定长的字符串
	 */
	public static String toFixdLengthString(long num, int fixdlenth) {

		StringBuffer sb = new StringBuffer();
		String strNum = String.valueOf(num);
		if ( fixdlenth - strNum.length() >= 0 ) {
			sb.append(generateZeroString(fixdlenth - strNum.length()));
		} else
			throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常！");
		sb.append(strNum);
		return sb.toString();
	}

	/**
	 * 根据数字生成一个定长的字符串，长度不够前面补0
	 * 
	 * @param num
	 *            数字
	 * @param fixdlenth
	 *            字符串长度
	 * @return 定长的字符串
	 */
	public static String toFixdLengthString(int num, int fixdlenth) {

		StringBuffer sb = new StringBuffer();
		String strNum = String.valueOf(num);
		if ( fixdlenth - strNum.length() >= 0 ) {
			sb.append(generateZeroString(fixdlenth - strNum.length()));
		} else
			throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常！");
		sb.append(strNum);
		return sb.toString();
	}

	// public static void main(String[] args) {
	// System.out.println(generateString(15));
	// System.out.println(generateMixString(15));
	// System.out.println(generateLowerString(15));
	// System.out.println(generateUpperString(15));
	// System.out.println(generateZeroString(15));
	// System.out.println(toFixdLengthString(123, 15));
	// System.out.println(toFixdLengthString(123L, 15));
	// }
	/** 生成邀请码 */
	public static String getInvitationCode(String mobile) {

		if ( StringUtils.isNotBlank(mobile) ) {
			String last4 = StringUtils.substring(mobile, mobile.length() - 4);
			String invitationCode = RandomUtils.generateString(6) + last4;
			return invitationCode;
		}
		return null;
	}

	/** 根据指定几率随机取值 */
	public static boolean roll(double rate) {

		boolean flag = false;
		Random random = new Random();
		int total = 100000;
		double r = random.nextInt(total);
		if ( r < total * rate ) {
			flag = true;
		}

		return flag;
	}
}
